This invention relates to a new and improved electromagnetic lock system for providing controlled access through a doorway by means of an electromagnetic lock. More particularly, this invention relates to a lock system wherein controlled access through a doorway is accomplished by means of an automatic electronic control system.
Electromagnetic locks which function to magnetically bond a door to the doorframe have proved very advantageous in satisfying both security and safety requirements and in providing efficient and reliable means for remote control and monitoring of an integrated multi-lock system. Electromagnetic locks have effectively eliminated the numerous disadvantages of the mechanical lock system such as mechanical failure or mechanical wear in the form of return spring breakage, bolt side loading or binding, and other mechanical malfunctions which may result in a lock system which is either ineffective for normal usage or non-functional in emergency situations. The electromagnetic lock provides many additional advantages such as centralized control and monitoring, ease of installation, and ease of maintenance due to the absence of moving parts.
The present invention is particularly adaptable for use in providing controlled access through one or more emergency doors such as, for example, a multiplicity of stairwell doors in a multi-story structure. Security requirements and building and fire-code regulations combine to define critical--and often conflicting--design constraints for any lock system which is to be employed for controlling access through emergency doors. From the security perspective, the function of the lock system is to prevent unauthorized entry through the doorway while controllably permitting egress through the doorway. In many applications such as secured institutions, it is critical that the lock system control authorized egress and discriminate against unauthorized egress. From the safety perspective, in the event of an emergency condition such as a fire, it is critical that egress through the doorway be easily accomplished in a prompt manner in which no special knowledge is required to unlock or disable the lock system. It is also critical that the door remain latched in a closed position in the absence of egress to prevent fire, water or smoke migration into the building core.
The use of centralized supervisory remote control and remote monitoring of multiple lock systems has become commonplace as a means for enhancing the security provided by multi-lock systems. Strict adherence to security and safety standards requires that the control and monitor functions be resourcefully allocated and coordinated between the local electromagnetic lock unit and the remote supervisory unit. Integration of the electromagnetic lock unit and the smoke detection system is als highly desirable.